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stormwater management for clean rivers
How to manage stormwater
Downspout
Disconnection
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how to
disconnect downspouts
Portland gets an average of 37 inches of rain a year. Rain that runs off your
roof can flow directly into a sewer pipe, stream or groundwater. Why not put
it to better use? You can disconnect your downspouts to redirect water to
your yard or garden. Containing rainwater from hard surfaces on
your property also reduces demand on the sewer system and protects
the quality of rivers, streams, and groundwater.
What is involved in disconnecting
my downspouts?
You can disconnect your downspouts from existing
standpipes and let it flow over landscaped areas or
lawns. Disconnection can be a low-maintenance
option to help move water away from building
foundations and allow it to soak into the ground.
Disconnecting includes cutting the downspout;
attaching elbows, extensions, and splashblocks to
direct the water to flow away from the house;
plugging the standpipe; and securing the materials
to existing structures.
Where do I start?
Begin by preparing a good plan to ensure that the
stormwater soaks into the ground without damaging your structures or neighboring structures. This
brochure describes a simple, four-step process to
help you disconnect your downspouts.
Other brochures in this series show you How to
build a rain garden, soakage trench, or rain barrel,
to manage the stormwater runoff. Refer to the
resources section on page 7 to learn how
to get copies.
Are there incentives?
When you contain the rain on your property, you
qualify for a discount on the stormwater portion
of your city utility bill. See the resources section
of this brochure for more information on
Clean River Rewards.
STORMWATER MANAGEMENT
HOW TO - DISCONNECT DOWNSPOUTS
CITY OF PORTLAND ENVIRONMENTAL SERVICES
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observe your site
1
F
ind out where runoff from your downspouts
goes, including your house, garage, and other
covered surfaces. Are your downspouts draining
to your lawn or are they connected to the sewer
system or to drywells? Downspouts that drain into
standpipes (pipes) may drain into a public sewer system, a curb cut ( a hole in the curb at the sidewalk),
soakage trench, a drywell, or other stormwater
drainage system. If your downspouts drain into
soakage trenches or drywells on your property and
are in good working order, you do not need to disconnect, but may want to in order to avoid future
maintenance or replacement costs.
To find out if you have soakage trenches or
drywells, call 503-823-7660 for plumbing permits
or building records on file for your property.
Draw what you see
Sketch a site plan. You can print an aerial view
of your property from PortlandMaps.com as a
starting point.
Mark the locations of downspouts and roof line and
estimate the square footage of your roof area. Map
out areas in your yard down slope of structures
where you might disconnect downspouts.
example site plan: locate existing downspouts
downspouts k
STORMWATER MANAGEMENT
Safety considerations
Slope: Add or remove soil to make sure that
the slope of the ground allows water to flow
away from structures. However, do not disconnect downspouts on slopes over 10%.
Drainage: Avoid disconnecting downspouts in
an area too small for good drainage (see page
4 for guidelines).
Extensions: Disconnected downspouts must
be extended to discharge water at least 6 feet
from a structure’s basement and 2 feet from a
structure’s crawl space or slab foundation.
Downspout extensions and surrounding landscape surface must drain water away from
any structures.
Property Lines: The end of your downspout
extension must be at least 5 feet from your
neighbors’ property line and 3 feet from the
public sidewalk. You may need more room
if your yard slopes towards your neighbor or
the sidewalk.
Access: Avoid disconnecting downspouts or
adding downspout extensions across a walkway, patio, driveway, or in front of a gate
because of possible tripping hazards.
Other Hazards: Do not disconnect directly
over a septic system, drain field, or an underground oil tank unless they have been decommissioned. Do not disconnect within ten feet
of a retaining wall.
HOW TO - DISCONNECT DOWNSPOUTS
CITY OF PORTLAND ENVIRONMENTAL SERVICES
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2
design your disconnection
M
ark downspouts to be disconnected on
your existing site plan. Mark where you
might pitch gutters, move downspouts,
remove walkways or other impervious areas, or add
extensions or elbows to get around plants or other
obstructions.
Make sure you have enough landscaped area for
rain to soak safely into the ground. The ground
area must be at least 10% of the roof area that
drains to the disconnected downspout.
For example, to drain 500 square feet of rooftop,
there should be at least 50 square feet of landscape.
roof area
500 sq. ft.
sizing factor landscaped area size
x 10%
= 50 sq. ft. (or 5’ x 10’)
House 1,260 ft 2
All splashblocksdisconnect to lawn
Walk
Driveway
Move/rehang
downspout
to north corner
Garage
300 ft 2
You may have more than one option for directing
each downspout. Consider combining elbows and extensions to
send water to the side or front,
or to get around obstacles and
drain water away from the
house. Downspouts can also be
relocated along the gutter to a
safe drainage location.
4
STORMWATER MANAGEMENT
Tools
You will need
a hacksaw, a
drill, a pair of
needle-nose
pliers or
crimpers, a tape
measure, and a
screwdriver or nut driver.
Materials
Make a list of the parts and materials needed.
Downspout elbows and extensions come in a few
standard shapes, sizes, colors, and materials to fit
your gutters. Ask if the materials you choose can
be painted to match your paint color or blend into
your landscaping. Sewer standpipes must be sealed
with a rubber cap secured by a hose clamp or
with a wing-nut test plug. Most standpipes are
between three and five inches wide. Measure the
inside diameter of yours before shopping.
Some downspouts are attached only to the gutter
and the sewer standpipe. If so, you may need to
secure your downspout to your house with a bracket or strap to keep it in place when you disconnect.
Use durable, gutter-grade materials such as
aluminum, steel, copper, vinyl, and plastic.
Black ABS SCH 40 plastic is a durable option
found in most hardware stores and home
centers. Do NOT use
corrugated black plastic
(ADS), roll-out-hose,
PVC pipe, dryer hose,
swivel or open-trough
materials because of
their limited durability.
HOW TO - DISCONNECT DOWNSPOUTS
CITY OF PORTLAND ENVIRONMENTAL SERVICES
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Other suggestions
q Consider installing a hinged downspout elbow
and enclosed extension that you can flip up
against the house during dry weather or lawn
mowing. The extension must be enclosed, not
an open trough. (see diagram 1)
q
r Think about creating a space to disconnect
by removing paved surfaces, such as concrete
pathways, patios or unused driveway area.
s Replace pavement or concrete with pavers
or gravel where appropriate to allow for
infiltration. (see diagram 3)
t Extend downspouts underneath a deck or
raised patio to get runoff to a landscaped area.
(see diagram 4)
u Use plastic or concrete splashblocks, rocks,
flagstone, or boulders at the end of downspouts to control erosion, help direct runoff,
and add visual interest. (see diagram 5)
s
v Incorporate other stormwater management
systems into your downspout disconnections,
such as a rain garden, soakage trench, or
rainwater harvesting system. See the
resources section for more information.
t
u
STORMWATER MANAGEMENT
HOW TO - DISCONNECT DOWNSPOUTS
CITY OF PORTLAND ENVIRONMENTAL SERVICES
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A-B
3
disconnect
All disconnections should meet the safety considerations
found on page 3 and the water should flow away from
all structures.
A Measure the existing downspout from the top of
the standpipe and mark it at about 9 inches above
the standpipe. You may need to cut the downspout
higher depending on the length of your extension.
C
B Cut the existing downspout with a hacksaw at the
mark. Remove the cut piece.
C Plug or cap the standpipe using an in-pipe test
plug or an over-the-pipe cap secured by a hose clamp.
Do NOT use concrete to seal your standpipe.
plug with wing nut
cap with hose clamp
D
D Attach the elbow. Be sure to attach the elbow OVER
the downspout. Do NOT insert the elbow up inside
the downspout or it will leak. If the elbow does not
fit over the downspout, use crimpers or needle-nose
pliers to crimp the end of the cut downspout so it
slides INSIDE the elbow.
E Measure and cut the downspout extension to the
desired length. Attach the extension to the elbow by
slipping the extension OVER the end of the elbow.
Do NOT install the elbow over the extension or it will
leak. The length of the extension will depend on site
conditions and where you want the downspout to drain.
E
• Downspouts must drain at least 6 feet from
basement walls and at least 2 feet from crawl
spaces and concrete slabs.
• The end of the downspout must be at least 5 feet from
your property line, and possibly more if your yard slopes
toward your neighbor’s house.
F Secure the pieces with sheet metal screws at each joint
where the downspout, elbow, and extension connect.
It helps to pre-drill holes for the screws.
F-G
G Using a splash block at the end of the extension is
optional, but it will help prevent soil erosion.
Total distance will depend on whether
or not you have a basement.
6
STORMWATER MANAGEMENT
HOW TO - DISCONNECT DOWNSPOUTS
CITY OF PORTLAND ENVIRONMENTAL SERVICES
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maintenance
resources
Proper maintenance of your gutters, downspouts,
and landscaping can reduce problems.
Clean River Rewards
4
Gutters:
• Clean at least twice a year, and more often
if you have overhanging trees.
• Make sure gutters are pitched to direct
water to downspouts.
• Caulk leaks and holes.
• Make sure roof flashing directs water
into the gutters.
• Look for low spots or sagging areas
along the gutter line and repair
with spikes or place new hangers
as needed.
Downspouts:
• Check and clear elbows or bends in downspouts
to prevent clogging.
Clean River Rewards is Portland’s stormwater discount program. When you contain the rain safely
on your property, you can save money with an ongoing discount on your city utility bill. Go to
www.CleanRiverRewards.com to register or to download publications to help you plan, build and maintain disconnected downspouts or other stormwater
management options. You can also find other technical assistance information and useful links. For more
information, call 503-823-1371.
Additional Information
Download all of the How to brochures and
find step-by-step video instructions for
How to Disconnect a Downspout and
How to Create a Rain Barrel online at
www.CleanRiverRewards.com
• Each elbow or section of the downspout should
funnel into the one below it. All parts should
be securely fastened together with sheet
metal screws.
City of Portland
Stormwater Management Manual:
www.portlandonline.com/bes/swmm
Landscaping:
• The ground should slope away from structures.
City of Portland Stormwater Solutions Handbook:
www.portlandonline.com/bes/stormwatersolutions
• Don’t build up soil, bark dust, or woodpiles
against the siding.
• Avoid draining water onto impermeable
plastic weed block or cloth.
STORMWATER MANAGEMENT
City of Portland Research and Records
503-823-7660
HOW TO - DISCONNECT DOWNSPOUTS
CITY OF PORTLAND ENVIRONMENTAL SERVICES
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Environmental Services
Dan Saltzman, Commissioner
Dean Marriott, Director
1120 SW Fifth Avenue
Portland Oregon, 97204
503-823-7740
www.portlandoregon.gov/bes
Other publications in this brochure series:
How to manage stormwater - Rain Gardens
How to manage stormwater - Soakage Trenchs
How to manage stormwater - Rain Barrels
To help ensure equal access to city programs,
services, and activities, the city will reasonably
accommodate persons with disabilities.
Call 503-823-7740 or 1-800-735-2900 with
such requests. TDD 503-823-6868.
ES 1112 rev May 2011